Escherichia coli (E. coli) is a gram-negative, rod-shaped bacterium. Although most strains of E. coli are benign and are found as normal intestinal flora of humans and other animals, some strains are pathogenic and can lead to disease. Different strains of pathogenic E. coli differ in their epidemiology, clinical course and potential for causing outbreaks of disease.
Shiga toxin producing Escherichia coli (STEC) is a type of enterohemorrhagic bacteria that can cause mild to severe intestinal disease, kidney problems, and even central nervous system effects. The pathogenicity of these bacterial strains is due, in large part, to their production of Shiga-like toxins Stx1 and Stx2. Additionally, production of the intimin adherence protein encoded by the eae gene has been linked to pathogenicity of bacteria, as has possession of certain surface antigens, including the O26, O111, O121, O45, O103, and O145 antigens.
One well-known serotype of STEC bacteria is E. coli serotype O157:H7, which has been associated with several food and water borne outbreaks. This bacterial serotype is regulated as an adulterant in ground beef by the U.S. Department of Agriculture (USDA) with a zero tolerance standard. Because of its tight regulation, numerous tests for E. coli O157:H7 exist in the market. However, numerous other STEC bacteria strains also can cause disease, making detection of other STEC bacterial serotypes, or STEC bacteria in general, important for improved food safety.
It is desirable, therefore, to have a test for the accurate detection and characterization of STEC bacteria in a sample.